The high-affinity IgE receptor, also known as FcεRI, or Fc epsilon RI, is the high-
affinityreceptor for the
Fc region of
immunoglobulin E (IgE), an
antibodyisotype involved in
allergy disorders and
parasite immunity. FcεRI is a
tetrameric receptor complex that binds Fc portion of the ε
heavy chain of
IgE.[1] It consists of one alpha (
FcεRIα – antibody binding site), one beta (
FcεRIβ – which amplifies the downstream signal), and two gamma chains (
FcεRIγ – the site where the downstream signal initiates) connected by two disulfide bridges on
mast cells and
basophils. It lacks the beta subunit on other cells. It is constitutively expressed on mast cells and basophils[2] and is inducible in
eosinophils.
FcεRI was demonstrated in bronchial/tracheal airway
smooth muscle cells in normal and asthmatic patients. FcεRI cross-linking by IgE and anti-IgE antibodies led to Th2 (IL-4, -5, and -13) cytokines and CCL11/eotaxin-1 chemokine release; and ([Ca2+]i) mobilization, suggesting a likely IgE-FcεRI-ASM (airway
smooth muscle cell)-mediated link to airway inflammation and
airway hyperresponsiveness.[7][8]
Mechanism of action
Crosslinking of the FcεRI via IgE-
antigen complexes leads to degranulation of mast cells or basophils and release of
inflammatory mediators.[9] Under laboratory conditions,
degranulation of isolated basophils can also be induced with
antibodies to the FcεRIα, which crosslink the receptor. Such crosslinking and potentially pathogenic
autoantibodies to the FcεRIα have been isolated from human
cord blood, which suggest that they occur naturally and are present already at birth. However, their
epitope on FcεRIα was masked by IgE, and the affinity of the corresponding autoantibodies found in healthy adults appeared lowered.[10]
^Kumar, Vinay; Abbas, Abul K.; Aster, Jon (2012-05-01).
Robbins Basic Pathology (9 ed.). Saunders.
^Pawankar R (February 2001). "Mast cells as orchestrators of the allergic reaction: the IgE-IgE receptor mast cell network". Current Opinion in Allergy and Clinical Immunology. 1 (1): 3–6.
doi:
10.1097/00130832-200102000-00002.
PMID11964662.
^Ochiai K, Wang B, Rieger A, Kilgus O, Maurer D, Födinger D, Kinet J, Stingl G, Tomioka H (1994). "A review on Fc epsilon RI on human epidermal Langerhans cells". International Archives of Allergy and Immunology. 104. Suppl 1 (1): 63–64.
doi:
10.1159/000236756.
PMID8156009.